Kumarajah Kandiah

Concentration and temperature-dependent low-field mobility model for in0.53Ga0.47As interdigitated lateral pin PD

The fitted parameters for the analytic function used to specify doping- and temperature-dependent low-field mobilities for In0.53Ga0.47As is described in this paper. The developed model was compared with other mobility models as well as measured Hall data from periodical literature and very good agreement is observed. The result of this work was used to develop an In0.53Ga0.47As interdigitated lateral p-i-n photodiode (ILPP) model and good correlation was obtained when compared with the experimentally developed device. The results of this work would be useful in the development of In0.53Ga0.47As-based devices using commercial device simulation packages.

Design and modeling of a vertical-cavity surface-emitting laser (VCSEL)

In this paper, we attempt to design, simulate and characterize an InGaAs-based vertical-cavity surface-emitting laser (VCSEL) employing InGaAsP multi-quantum wells sandwiched between GaAs/AlGaAs and GaAs/AlAs distributed Bragg reflectors using an industrial-based numerical simulator. We were able to obtain a working model at an optical wavelength of 1.55 mum. This paper provides key results of the device characteristics including the DC V-I and the light power versus electrical current. Effect of DBR mirror stack quantities were also experimented with and the results are reported here.

The Development of a new Responsivity Prediction Model for In0.53Ga0.47As Interdigitated Lateral p-i-n Photodiode

The interdigitated lateral p-i-n photodiode (ILPP) has profound advantages compared to the vertical p-i-n photodiode (VPD) structure mainly due to the ease of fabrication where diffusion or ion implantation can be used to form the p+ and n+ wells in the absorbing layer. A novel ILPP model utilizing In 0.53 Ga 0.47 As (InGaAs) as the absorbing layer was developed and optimized statistically using fractional factorial design (FFD) methodology. Seven model factors were investigated and a new analytical equation was developed to predict the responsivity of ILPP devices as a function of design factors. Comparison between the simulated and calculated responsivity values yielded error ratios of less than 3 %. A statistically optimized ILPP model with -3 dB frequency of 7.5 GHz, responsivity of 0.61 A/W and signal-to-noise ratio (SNR) of 20 dB was developed at an operating voltage of 5 V, wavelength of 1.55 μm and optical input power of 10 Wcm -2 . Hence the model qualifies to be used as a cheap and affordable device in fiber-to-the-home based on passive-optical-networks (FTTH-PON) operating at a minimum speed of 2.5 Gbps.

VARIATION OF MQW DESIGN PARAMETERS IN A GaAs/InP-BASED LW-VCSEL AND ITS EFFECTS ON THE SPECTRAL LINEWIDTH

This paper reports on the simulative and comparative study on the effects of multi quantum well (MQW) design parameters on the spectral linewidth of a wafer-bonded GaAs/InP-based, 1.5 μm long-wavelength vertical-cavity surface-emitting laser (LW-VCSEL). The device employs InGaAsP MQWs sandwiched between GaAs/AlGaAs and GaAs/AlAs distributed Bragg reflectors (DBR) and utilizes a bottom-emitting, air-post design for current confinement. Among the modeled LW-VCSEL devices, the best linewidth achieved was 41.29 MHz at a peak wavelength of 1.57 μm for 8 MQWs with well thicknesses of 5.5 nm each and barrier thicknesses of 8 nm; equivalent to the experimental device developed in the past. Comparison of linewidth values calculated using developed analytical equations that link the MQW parameters to the spectral linewidth versus the actual linewidth from fabricated devices yields error ratios of ~ 6% proving a robust approximation has been achieved.

SNR prediction model of an In 0.53 Ga 0.47 As interdigitated lateral p-i-n photodiode

The In0.53Ga0.47As interdigitated lateral p-i-n photodiode (ILPP) is a a cheap and affordable device to meet growing demands of optical communication networks operating at speeds below 10 Gbps. A ILPP model utilizing In0.53Ga0.47As as the absorbing layer was developed and optimized statistically using fractional factorial design (FFD) methodology. Seven model factors were investigated and a new analytical equation was developed to predict the signal-to-noise (SNR) ratio of ILPP devices as a function of design factors. The analytical equation was used to predict SNR values for experimentally developed devices from the literature.

An interdigitated diffusion-based In(0.53)Ga(0.47)As lateral PIN photodiode

A novel 3D modeling of a lateral PIN photodiode (LPP) is presented utilizing In0.53Ga0.47As as the absorbing layer. The LPP has profound advantages compared to the vertical PIN photodiode (VPD) mainly due to the ease of fabrication where diffusion or ion implantation can be used to form the p+ and n+ wells in the absorbing layer. The device has an interdigitated electrode structure to maximize optical absorption. At a wavelength of 1550 nm, optical power of 5 Wcm-2 and 5 V reverse bias voltage, the device achieved responsivity of 0.5 A/W. The -3dB frequency response of the device was at 14 GHz and it is able to cater for 10 Gbit/s optical communication networks.

NEAR FIELD AND FAR FIELD EFFECTS IN THE TAGUCHI-OPTIMIZED DESIGN OF AN InP/GaAs-BASED DOUBLE WAFER-FUSED MQW LONG-WAVELENGTH VERTICAL-CAVITY SURFACE-EMITTING LASER

Long-wavelength VCSELs (LW-VCSEL) operating in the 1.55 μm wavelength regime offer the advantages of low dispersion and optical loss in fiber optic transmission systems which are crucial in increasing data transmission speed and reducing implementation cost of fiber-to-the-home (FTTH) access networks. LW-VCSELs are attractive light sources because they offer unique features such as low power consumption, narrow beam divergence and ease of fabrication for two-dimensional arrays. This paper compares the near field and far field effects of the numerically investigated LW-VCSEL for various design parameters of the device. The optical intensity profile far from the device surface, in the Fraunhofer region, is important for the optical coupling of the laser with other optical components. The near field pattern is obtained from the structure output whereas the far-field pattern is essentially a two-dimensional fast Fourier Transform (FFT) of the near-field pattern. Design parameters such as the number of wells in the multi-quantum-well (MQW) region, the thickness of the MQW and the effect of using Taguchis orthogonal array method to optimize the device design parameters on the near/far field patterns are evaluated in this paper. We have successfully increased the peak lasing power from an initial 4.84 mW to 12.38 mW at a bias voltage of 2 V and optical wavelength of 1.55 μm using Taguchis orthogonal array. As a result of the Taguchi optimization and fine tuning, the device threshold current is found to increase along with a slight decrease in the modulation speed due to increased device widths.

Numerical Modeling of a Diffusion-Based In0.53Ga0.47As Lateral PIN Photodiode for 10 Gbit/s Optical Communication Systems

A novel purely diffusion-based In0.53Ga0.47As lateral PIN photodiode was successfully modeled. Device dimensions are 12 times 1.8 mum2 with electrode spacing of 1.5 mum and width of 1 mum. The effective intrinsic region width is ~0.2 mum. The 2D modeled device achieved responsivity of 0.765 AAV and -3 dB frequency of 10.9 GHz and is able to cater for 10 Gbit/s optical communication system networks. The device was biased at -2V and illuminated with a 5 W/cm2 optical spot power at a wavelength of 1.55 mum. SNR ratio was recorded at 31.2 dB.

Beam propagation method study of wavelength dependent in directional coupler switch

Different coupling efficiencies experienced by different wavelengths have been observed in directional couplers by a BPM study. This behaviour continues to be observed in electro-optic directional couplers, such as LiNbO/sub 3/, when an external voltage is being applied. This property can lead to the development of a device which has the ability to manage the distribution of various optical wavelengths between 1.10 /spl mu/m and 1.55 /spl mu/m under the application of external voltages of <10 V.

Novel 3D modeling of In0.53Ga0.47As lateral PIN photodiode

The lateral PIN photodiode (LPP) can be fabricated with ease using standard CMOS techniques such as diffusion or ion implantation to form the p+ and n+ wells in the absorbing layer. A novel diffusion-based three-dimensional LPP was modeled utilizing In0.53Ga0.47As as the absorbing layer. Interdigitated electrode structures were used to obtain responsivity of ~0.5-0.6 A/W and -3dB frequency of ~14-15 GHz at a wavelength of 1550 nm, bias voltage of 5V and optical power of 10 Wcm-2. The modeled device is able to cater for 10 Gbit/s optical communication networks.